Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
  • C08G59/4014—Nitrogen containing compounds
  • C08G59/4042—Imines; Imides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/42—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
  • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
  • C08L33/062—Copolymers with monomers not covered by C08L33/06
  • C08L33/064—Copolymers with monomers not covered by C08L33/06 containing anhydride, COOH or COOM groups, with M being metal or onium-cation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F1/00—Shielding characterised by the composition of the materials
  • G21F1/02—Selection of uniform shielding materials
  • G21F1/10—Organic substances; Dispersions in organic carriers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0073—Shielding materials
  • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
  • H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/08—Metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
  • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
  • C08L33/062—Copolymers with monomers not covered by C08L33/06
  • C08L33/068—Copolymers with monomers not covered by C08L33/06 containing glycidyl groups
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/32—Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer

Definitions

• the present invention relates to an electromagnetic wave-absorbing material and, particularly to an electromagnetic wave-absorbing material which is suitably usable for various devices and apparatuses such as electronic devices.
• the electromagnetic wave absorbers are produced in the form of a flexible sheet, and can reduce the noise due to electromagnetic waves by a method wherein the electromagnetic wave absorber is attached or bonded to, or is wrapovered an electromagnetic wave- emitting source.
• the electromagnetic wave absorbers are usually called electromagnetic wave- absorbing sheets, noise-suppression sheets, etc.
• an electromagnetic wave absorber one comprising chlorinated polyethylene and soft magnetic powder mixed therein is known (as disclosed in Patent Document 1).
• this electromagnetic wave absorber has a problem that it produces a halogen-containing gas when the absorber is incinerated to be disposed.
• the conventional electromagnetic wave absorbers cause various kinds of problems.
• the conventional electromagnetic wave absorbers have a tendency such that they have an insufficient strength, have a poor resistance to chemical agents, cause a problem of blocking, have a poor heat resistance, etc.
• an electromagnetic wave absorber using a silicone rubber has also been proposed (as disclosed in Patent Document 3).
• an impurity contained in the silicone rubber can deteriorate the electronic devices as the objects to which the electromagnetic wave absorbers are to be applied.
• An object of the present invention is to provide an electromagnetic wave absorber, which can solve the problem encountered in the prior art as described above.
• Another object of the present invention is to provide an electromagnetic wave absorber, which has sufficient electromagnetic wave-absorbing property, flexibility, good strength, and resistance to chemical agents, and good heat resistance.
• the present inventors have found that the above- mentioned object has been achieved, by a composition comprising a compound having two or more carboxyl groups in one molecule thereof, a multi-functional epoxide compound, and soft magnetic powder and thermally curing the composition comprising these compounds.
• the present inventors have accomplished the present invention based on this discovery. More specifically, the present invention includes, e.g., the following embodiments [l]-[7].
• An electromagnetic wave-absorbing material composition comprising: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound; (B) a compound having two or more epoxy groups in one molecule thereof; and (C) a soft magnetic powder.
• the soft magnetic powder is an amorphous metal, a soft magnetic metal or a ferrite compound.
• An electromagnetic wave absorber which has been provided by subjecting an electromagnetic wave-absorbing material composition to a crosslinking reaction, wherein the electromagnetic wave-absorbing material composition comprises: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound; (B) a compound having two or more epoxy groups in one molecule thereof; and (C) a soft magnetic powder.
• An electromagnetic wave-absorbing sheet which has been provided by subjecting an electromagnetic wave- absorbing material composition to a crosslinking reaction, wherein the electromagnetic wave-absorbing material composition comprises: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound; (B) a compound having two or more epoxy groups in one molecule thereof; and (C) a soft magnetic powder.
• the electromagnetic wave absorber may preferably contain substantially no halogen atom (more preferably 0.2 mass % or less, based on the total mass of the electromagnetic wave absorber).
• the electromagnetic wave-absorbing material composition according to the present invention is a composition, which comprises: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound, (B) a compound having two or more epoxy groups in one molecule thereof, and (C) a soft magnetic powder.
• the electromagnetic wave absorber according to the present invention can be obtained, e.g., by thermally curing (or crosslinking) a composition, which comprises: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound, (B) a compound having two or more epoxy groups in one molecule thereof, and (C) a soft magnetic powder.
• a composition which comprises: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound, (B) a compound having two or more epoxy groups in one molecule thereof, and (C) a soft magnetic powder.
• Component (A) The compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound, as Component (A), may preferably be a polymer compound having a relatively high molecular weight.
• the molecular weight may preferably be lxlO 4 or more, more preferably 2xl0 4 or more, further preferably 5xl0 4 or more, in terms of the weight-average molecular weight (i.e., molecular weight in polystyrene conversion as determined by GPC (gel permeation chromatography) measurement).
• the molecular weight may preferably be 1x10 s or less, more preferably 5x10 s or less.
• Component (A) may preferably be a rubberlike (or elastomeric) polymer compound.
• the resultant electromagnetic wave absorber has an appropriate flexibility, and therefore it can be attached or applied to an electromagnetic wave-generating source having various kinds of shapes so as to provide a close or intimate contact therebetween.
• the "rubberlike polymer compound” refers to a polymer compound showing a so-called rubber-like elasticity at normal (or room) temperature (e.g., 25°C).
• the polymer compound showing a rubber-like elasticity may preferably be one having a Tg (glass transition point) of 0°C or lower.
• Tg glass transition point
• Tg may be measured by DSC (JIS K7121).
• Examples of the Component (A) may include: homopolymers of monobasic carboxylic acid or ester thereof having at least one double bond (such as acrylic acid, methacrylic acid, and vinyl acetate), and copolymers thereof with another monomer, and hydrogenated products of these polymers; copolymers of a dibasic acid having at least one double bond (such as maleic acid) and/or acid anhydrides thereof (such as maleic anhydride, and Himic anhydride (i.e., 5-norbornene-2,3-dicarboxylic anhydride)) and another monomer; products obtained by reacting a poly carboxylic acid and a polyol; products obtained by the addition reaction of a multivalent (or polybasic) carboxylic acid with an epoxide compound; products obtained by the addition reaction of an acid anhydride with a compound having a hydroxyl group, etc.
• homopolymers of monobasic carboxylic acid or ester thereof having at least one double bond such as acrylic acid, me
• Examples of the above copolymerizable "another monomer” may include: acrylic acid esters such as ethyl acrylate and methyl acrylate, methacrylic acid esters such as methyl methacrylate, and monomers having an ethylenically unsaturated bond such as styrene, acrylonitrile, ethylene, propylene, and vinyl acetate.
• Specific examples of the Component (A) may include: VamacTM G, VamacTM GLS, and VamacTM HVG which are acid- modified ethylene acrylic rubbers (mfd.
• NipolTM 1072 NipolTM 1072J
• NipolTM DN631 which are acrylonitrile-butadiene- methacrylic acid copolymers (mfd. by Nippon Zeon Co.,Ltd.), and the hydrogenated product of these polymers, and compounds having two or more carboxyl groups and/or acid anhydride group thereof. These compounds may be used singly or as a mixture or combination of two or more kinds thereof.
• Component (B) The compound having two or more epoxy groups in one molecule thereof (Component (B)) usable in the present invention is not particularly limited, as long as it has a reactivity with the above-mentioned Component (A) .
• specific examples of the Component (B) may include: e.g., bispenol A-type epoxy resins, hydrogenated bispenol A-type epoxy resins, brominated bispenol A-type epoxy resins, bisphenol F-type epoxy resins, Novolak-type epoxy resins, phenol Novolak- type epoxy resins, cresol Novolak-type epoxy resins, Novolak-type epoxy resins of bispenol A, chelate-type epoxy resins, glyoxal-type epoxy resins, polysulfide-type epoxy resins, amino group-containing epoxy resins, rubber-modified epoxy resins, dicyclopentadiene phenolic- type epoxy resins, silicone-modified epoxy resins,
• the electromagnetic wave-absorbing material according to the present invention may also contain a rubber (or rubber-like) component having no carboxyl group, and/or an epoxide compound having one epoxy group in one molecule thereof, as desired.
• the rubber component may include: rubber components having no carboxyl group, such as NBR (acrylonitrile-butadiene rubber), silicone rubbers, chlorinated polyethylenes, EPR (ethylene-propylene rubber), EPDM, (ethylene-propylene- diene terpolymer), polyurethane rubbers, olefinic-type thermoplastic elastomers, and styrene-type thermoplastic elastomers .
• NBR acrylonitrile-butadiene rubber
• silicone rubbers chlorinated polyethylenes
• EPR ethylene-propylene rubber
• EPDM ethylene-propylene- diene terpolymer
• polyurethane rubbers olefinic-type thermoplastic elastomers
• styrene-type thermoplastic elastomers styrene-type thermoplastic elastomers
• the amount of the rubber component having no carboxyl group, and/or epoxide compound having one epoxy group in one molecule thereof is not particularly limited, as long as they does not substantially impair the characteristic of the composition according to the present invention, in view of the strength and heat resistance, the amount of the rubber component having no carboxyl group, and/or epoxide compound having one epoxy group in one molecule thereof may preferably be 15 mass parts or less (more preferably 10 mass parts or less), with respect to the total 100 mass parts of the above- mentioned Components (A) and (B).
• the amount of the compound (A) having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound may preferably be 25-99 mass parts, with respect to 100 mass parts of the subtraction weight, which has been obtained by subtracting the weight of the soft magnetic powder (C) from the total weight of the electromagnetic wave-absorbing material composition. That is, when the total weight of the electromagnetic wave-absorbing material composition is denoted by Wt, and the weight of the soft magnetic powder (C) is denoted by Wc, the subtraction weight Ws is (Wt-Wc).
• Wt total weight of the electromagnetic wave-absorbing material composition
• Wc weight of the soft magnetic powder
• the subtraction weight Ws is (Wt-Wc).
• the amount of the compound (A) exceeds 99 mass parts, the tensile strength and resistance to chemical agents are also liable to be decreased.
• the amount of the compound (B) having two or more epoxy groups in one molecule thereof may preferably be 50-1 mass parts, with respect to 100 mass parts of the subtraction weight, which has been obtained by subtracting the weight of the soft magnetic powder (C) from the total weight of the electromagnetic wave-absorbing material composition.
• the amount of the compound (B) exceeds 50 mass parts, the flexibility is liable to be deteriorated.
• the "soft magnetic powder” refers to a powder of a material, which is ferromagnetic and has a high magnetic permeability and a low coercivity.
• the soft magnetic powder (C) to be used in the present invention may preferably have a good magnetic permeability in a high frequency range. More specifically, the soft magnetic powder (C) may more preferably have a magnetic permeability maximum value of 50 or more in high-frequency range of 1 MHz-10 GHz.
• the soft magnetic powder (C) may include: e.g., Permalloy, Sendust, Fe-Si, Fe-Si-Cr, carbonyl iron, and amorphous soft magnetic metals such as Fe-Si-B type material. Further, it is also possible to use oxide-type ferrite, such as Mn-Zn ferrite, and Ni-Zn ferrite.
• the soft magnetic powder (C) usable in the present invention is not particularly limited to the above specific examples thereof, but may be selected from wide range of soft magnetic powders .
• the shape or form of the soft magnetic powder is not particularly limited, but may be any of spherical, granular and flat or oblate-type powders. These soft magnetic powders may be used singly or as a mixture of two or more kinds thereof .
• the particle size of the soft magnetic powder is not particularly limited, but may preferably be 1-500 ⁇ m, more preferably 10-200 ⁇ m, particularly 10-80 ⁇ m, in terms of the average particle size D50 as measured by a laser diffraction particle size distribution analyzer.
• D50 denotes the median valve based on mass.
• the thickness "t" of the soft magnetic powder may preferably be 0.1-10 ⁇ m, more preferably 0.1-5 ⁇ m, particularly 0.1-2 ⁇ m, in terms of the average thickness as measured by a scanning electron microscope.
• the average aspect ratio may preferably be 1-1000, more preferably 5-200, particularly 10-100, in terms of the ratio (D50/t), which has been determined from the average particle size D50 as measured by a laser diffraction particle size distribution analyzer, and the average thickness "t” as measured by a scanning electron microscope.
• the average aspect ratio usable in the present invention is not limited to these specific ranges.
• the amount of the soft magnetic powder (C) in the composition according to the present invention may preferably be 200-900 mass parts, more preferably 300-900 mass parts, with respect to 100 mass parts of the subtraction weight, which has been obtained by subtracting the weight of the soft magnetic powder (C) from the total weight of the electromagnetic wave- absorbing material composition.
• the amount of the soft magnetic powder (C) is less than 200 mass parts, the electromagnetic wave-absorbing property is liable to be insufficient.
• the amount of the soft magnetic powder (C) exceeds 900 mass parts, the flexibility is liable to be deteriorated.
• the composition according to the present invention can contain at least one of various additives such as antioxidants, age resistors, fire retardants, fire retardant aids, plasticizers, curing (or crosslinking) agents, and solvents.
• the amount of the additive(s) is not particularly limited, as long as the addition of such an additive does not substantially impair the characteristic of the composition according to the present invention.
• the fire retardant may preferably be one containing no bromine, but may be phosphorus-containing compounds such as polyphosphoric acid ammonium and polyphosphoric acid melamine, and thermally expanding graphites, metal hydrates, etc.
• the catalyst When the electromagnetic wave-absorbing material composition according to the present invention is cured or crosslinked, it is possible to use various catalysts (or curing agents), as desired. In view of the handling thereof and a uniform or homogeneous reaction therefor, the catalyst may preferably be a thermal curing catalyst.
• Thermal curing catalyst (E)) The thermal curing catalyst (E) to be used in the present invention is not particularly limited, as long as the electromagnetic wave-absorbing material composition according to the present invention can be cured or hardened by such a catalyst.
• Preferred examples of the thermal curing catalyst (E) usable in the present invention may include: amines such as primary amines, secondary amines, and tertiary amines; amine salts such as chlorides of these amines; quaternary ammonium salts; acid anhydrides such as alicyclic acid anhydrides, aliphatic acid anhydrides and aromatic acid anhydrides; polyamides, nitrogen-containing heterocyclic compounds such as imidazole and triazine compounds; and organometallic compounds, etc. These catalysts may be used singly or as a mixture or combination of two or more kinds thereof, as desired. (Production process)
• the process for producing the electromagnetic wave- absorbing material composition according to the present invention is not particularly limited.
• the electromagnetic wave-absorbing material composition according to the present invention is produced by mixing the respective components constituting the composition, it is possible to use a kneading machine such as a kneader, a mixing roll, and an intensive mixer, or to dissolve or disperse the respective components in a solvent.
• a kneading machine such as a kneader, a mixing roll, and an intensive mixer, or to dissolve or disperse the respective components in a solvent.
• the method of processing or molding the electromagnetic wave-absorbing material composition according to the present invention is not particularly limited.
• the electromagnetic wave-absorbing material composition according to the present invention is formed into a desired shape, it is possible to use a molding method such as roll molding, extrusion molding, press molding, and injection molding, or a method wherein the electromagnetic wave-absorbing material composition is dissolved or dispersed into a solvent, the resultant solution or dispersion is applied onto an appropriate substrate, and then the resultant coating is dried. It is also possible to combine a plurality of these molding methods, as desired.
• the electromagnetic wave-absorbing material composition after the molding thereof is intended to be crosslinked, it is possible to adopt an arbitrary method such as one wherein the composition is placed in a heating furnace, or the composition is cured or crosslinked while being pressed by a heat press.
• Example 1 According to the formulation as shown in Table 1 appearing hereinafter, 97 g of VamacTM G (mfd. by Mitsui- Dupont Polychemical Co.) as a compound (A) having a carboxyl group and/or an acid anhydride group thereof; 3 g of FlepTM 60 (mfd. by Toray Finechemical Co.) as a compound (B) having two or more epoxy groups in one molecule thereof; and 0.15 g of CuresolTM 2MA-OK (mfd. by Shikoku Kasei Co., Ltd.) which is 2-aminoimidazole isocyanuric acid adduct as a curing agent were dissolved in 400 g of toluene.
• VamacTM G mfd. by Mitsui- Dupont Polychemical Co.
• FlepTM 60 mfd. by Toray Finechemical Co.
• CuresolTM 2MA-OK mfd. by Shikoku Kasei Co., Ltd.
• the resultant coating layer was peeled from the silicone- coated PET film, to thereby obtain an electromagnetic wave-absorbing material composition having a formulation as shown in Table 1 appearing hereinafter.
• the thus obtained electromagnetic wave-absorbing material composition was subjected to crosslinking in a heat press (pressure: 5 MPa) at 150°C for one hour, to thereby obtain a 100 ⁇ m-thick sheet-shaped sample of the electromagnetic wave absorber.
• Comparative Example 1 An electromagnetic wave absorber sample was obtained in the same manner as in Example 1, except that VamacTM D (mfd. by Mitsui/Dupont Polychemical Co. ) having no carboxyl group was used instead of Vamac G used in Example 1.
• the formulation used herein is shown in Table 1 appearing hereinafter.
• Comparative Example 2 An electromagnetic wave-absorbing material composition was obtained in the same manner as in Example 1 , except that the epoxide compound and the curing agent were not used. The thus obtained composition was subjected to pressing (pressure: 5 MPa) at normal temperature (i.e., without crosslinking), to thereby obtain a 100 ⁇ m-thick sheet-shaped sample of the electromagnetic wave absorber.
• Example 2 Comparative Examples 3-4 Each of the electromagnetic wave absorber samples was obtained in the same manner as in Example 1, except for using the corresponding electromagnetic wave- absorbing material composition having a formulation as shown in Table 1 appearing hereinafter.
• Examples 3-8 Each of the 100 ⁇ m-thick sheet-shaped electromagnetic wave absorber samples was obtained in the same manner as in Example 1, except for using the corresponding components according to the formulation as shown in Table 3 appearing hereinafter. More specifically, in these examples, VamacTM G (mfd. by Mitsui-Dupont Polychemical Co.) and/or NipolTM 1072J (mfd.
• Electromagnetic wave absorption ratio An electromagnetic wave absorber sheet (50 mm x 50 mm x 0.1 mm thickness) to be evaluated was placed on the microstrip line (characteristic impedance 50 ⁇ ) connected to a network analyzer (HP8510, mfd. by Hewlett- Packard Co.), and the electromagnetic wave absorption ratio of the sheet was evaluated from the transmission loss S21 of the S-parameter.
• the values of the S21 of the respective samples at 3 GHz, which were measured by the above method are shown in Tables 2 and 4 appearing hereinafter.
• the present invention provides an electromagnetic wave-absorbing material composition which includes: (A) a compound having two or more carboxyl groups and/or an acid anhydride group thereof, in one molecule of the compound; (B) a compound having two or more epoxy groups in one molecule thereof; and (C) a soft magnetic powder.
• the present invention may also provide an electromagnetic wave absorber which contains substantially no halogen (the halogen atom content may preferably be 0.2 mass % or less), and is excellent in flexibility, chemical resistance, and strength.

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  • 2004-08-18 KR KR1020067003053A patent/KR100781119B1/ko not_active IP Right Cessation
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